shep01- I seem to be the official Griot's Boar's Hair Brush fanatic around here. Glad to hear you like the brush. We beat this one to death on a few threads a while back, so I'm not gonna ramble on too much ( a search on Boar's/Boars Hair might bring it up). Some people get marring, others don't. But some people get marring with chenille mitts, too. Someone claims to have had Scottwax test one out and said they concluded that it didn't mar the finish they were testing it on; someone ELSE found that it did mar a black BMW. It ABSOLUTELY does not mar some vehicles, so if it works for you, keep using it. Note that there are a lot of different boar's hair brushes out there, and I sent back a few (to Griot's) that didn't pass muster.
IMHO, the best things about the brush are 1) ease of use 2) perfectly clean rinsing 3) durability (but don't expect the nice, soft flagged tips to last/stay flagged forever). Because of the free-rinsing, you're not gonna get a speck of something abrasive stuck in it and swirl up your entire car (assuming the two bucket method, of course).
The one for wheels is SUPERB and the smaller ones are perfect for nooks and crannies. The flow-through one isn't so soft so use it at your own risk.